Are there codes without a CEL?

[billzilla]

I have another car that was throwing a misfire code but no check engine light was on. Is this true of the Expo? Some codes don't cause the CEL?

 

[billzilla]

I answered my own question - nope, no codes.

 

[ELVATO]

Yea, it's possible that the condition is not yet bad enough to trip the CEL.

 

[Butch Smith]

Had number 4 coil go out and did not throw any codes